feat(mobile): haptic tick on PTT press/release and on reactions (#125)

utils/haptics.ts: tick('ptt-on' | 'ptt-off' | 'reaction') → 10/10/8 ms
navigator.vibrate, a no-op without the API (iOS), when the system prefers
reduced motion, or when the new Settings → Calls "Haptic Feedback" switch
(default on, only rendered where the API exists) is off. PTT is observed
once through pttActiveAtom so the keyboard, global-hotkey and on-screen
paths all tick; reactions tick where the reaction event is sent in the
room and thread timelines (quick bar, hover bar, sheet and emoji board
all funnel there).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/utils/haptics.ts

@@ -0,0 +1,26 @@
+/**
+ * [Gitea #125] Tiny vibration ticks for touch feedback. Android Chrome/PWA
+ * only — iOS has no web vibration API — and nothing at all when the user
+ * prefers reduced motion. Every call is a cheap no-op elsewhere.
+ */
+export type HapticKind = 'ptt-on' | 'ptt-off' | 'reaction';
+
+const PATTERN: Record<HapticKind, number> = { 'ptt-on': 10, 'ptt-off': 10, reaction: 8 };
+
+export const hapticsSupported = (): boolean =>
+  typeof navigator !== 'undefined' && typeof navigator.vibrate === 'function';
+
+const reducedMotion = (): boolean =>
+  typeof window !== 'undefined' &&
+  typeof window.matchMedia === 'function' &&
+  window.matchMedia('(prefers-reduced-motion: reduce)').matches;
+
+/** Fire a tick; returns whether one was requested. */
+export function tick(kind: HapticKind, enabled = true): boolean {
+  if (!enabled || !hapticsSupported() || reducedMotion()) return false;
+  try {
+    return navigator.vibrate(PATTERN[kind]) === true;
+  } catch {
+    return false;
+  }
+}